The invention relates to a method for the production of foamed elements from a mixture containing alkali metal silicate solution (waterglass), inorganic fillers, wetting agents and hardeners, which is mechanically foamed, brought into the form of the desired element and thus cured.
The production of foamed elements from waterglass foam is known as recited in German Published Applications DE-OS No. 19 05 340 and DE-OS No. 21 57 371. The foaming is effected either by chemical expanding agents or by the blowing in or stirring in of gases such as air or steam. In the present context, however, only mechanical foaming, in particular by the stirring in of air, is of interest.
Such shaped elements formed on the basis of cured waterglass foam are suitable primarily for use as insulating material, both for heat insulation and soundproofing in the building trade. Of particular importance in this connection are moisture stability and high flameproofness.
The known methods for the production of shaped elements on the basis of cured waterglass foam have, however, not led to satisfactory products. The method known from DE-OS No. 19 05 340 requires much energy and leads to foam materials with inhomogeneous pore distribution and, accordingly, inhomogeneous thermal conductivity. The foamed elements made according to DE-OS No. 21 57 371 are, above all, not sufficiently moisture resistant. With the use of the known methods, difficulties have arisen in the course of the process as well as in handling the finished product.